Control system for elevators



Dec. 12, 1961 w. STELZER 3,012,634

CONTROL SYSTEM FOR ELEVATORS Filed Dec. 11, 1958 2 Sheets-Sheet 1 I N VEN TOR.

Dec. 12, 1961 w. STELZER 3,012,634

CONTROL SYSTEM FOR ELEVATORS Filed Dec. 11, 1958 2 Sheets-Sheet 2 IN VEN TOR.

United States Patent Office 3,012,634 Patented Dec. 12, 1961 3,012,634 CONTROL SYSTEM FOR ELEVATORS William Stelzer, 4351 Franklin Road, Bloomfield Hills, Mich. Filed Dec. 11, 1958, Ser. No. 779,719 11 Claims. (Cl. 187-12) The invention relates to elevators and more particularly to a control system for small vertical or inclined elevators that are driven by an electric motor.

The object of the invention is to provide a novel system where an elevator car or platform is driven by an electric motor while ascending, and where the elevator car or platform is disengaged from the motor or driving mechanism during the descent so that the elevator car or platform can descend at a higher speed.

Another object is to provide a system where the otherwise conventional brake for stopping the machine at the end of the ascent is eliminated and where the car is stopped simply by disengaging the drive mechanism, means being provided to prevent back sliding of the car after it has come to a stop, an important advantage being a greatly reduced stopping distance.

A further object is to include a governor in the system for controlling the downward speed of the car and to compensate for the load so that the downward speed is the same when the car is empty or loaded, or that the speed is greater when the car is empty.

The general aim is to provide a mechanism that is cheaper to manufacture and requires less attention in use than present known constructions.

Other objects and advantages of this invention will be apparent from the following description considered in connection with the accompanying drawing submitted for the purpose of illustration and not to define the scope of the invention, reference being had for that purpose to the subjoined claims. In the drawings, wherein similar reference characters refer to similar parts throughout the several views:

FIG. 1 is a sectional elevation of the drive mechanism of the elevator;

FIG. 2, a section taken on line 22 of FIG. 1;

FIG. 3, a section taken on line '33 of FIG. 1 shown in a position assumed when the car is empty;

FIG. 4, the same section as FIG. 3, but showing the position when the car is loaded;

FIG. 5, an enlarged detail view of a vane used in the governor shown in FIG. 2;

FIG. 6, a partial section as viewed in the direction of arrows 6-6 of FIG. 1;

FIG. 7, a section taken on line 77 of FIG. 1;

FIG. 8, a diagram showing the electrical connections of the system; and

FIG. 9, a side elevation showing the novel mechanism in an inclined position incorporated in an inclined stair elevator.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of elements illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not limitation.

Describing the invention now in detail and referring in particular to FIG. 1, there is shown a channel-shaped frame 1 serving as a base to which a gear motor 2 is mounted. This gear motor consists of an electric motor 3 attached to a speed reducer 4 of the worm and gear type having a driven shaft 4' carrying a sprocket gear 5 to drive a chain 6 engaging a larger sprocket gear 7 secured to or a part of a hub 8 of a clutch indicated in general by numeral 9. The hub 8 is supported by a fixed stud 10 and anti-friction bearing 11 and revolves around a shaft 12 whose left end in turn is revolubly supported through an anti-friction bearing 14 by a stud 15 extending from a lever 16 pivoted at 17 to a bracket 18 ex tending from frame 1. A spring 13 interposed between frame 1 and an extension of lever 16 serves to urge lever 16 into a released position, as shown. Studs 10 and 15 have ball shaped heads fitting into the inner races of bearings 11 and 14 so that the bearings are always in axial alignment with shaft 12 or the axis of the clutch. The outer race 19 of bearing 14 is firmly secured to shaft 12 to be a part thereof. A drum 20 is rigidly secured to shaft 12 to turn therewith. It carries a spider 21 having fingers 22 engaging notched friction discs 24 so that the latter cannot turn relative to spider 21. Hub 8 has splines 25 carrying clutch plates 27 positioned intermediate the friction plates 24. Clutch plate 29 is rigid with hub 8 as this plate takes the thrust when the clutch is engaged. The other clutch plates 27 as well as the friction plates 24 are free to move endwise as required when the clutch is engaged or released. The drum 20 is the equivalent of a cable drum of a conventional elevator and carries a towing member in the form of a metallic tape or ribbon 30 secured by means of a pin 31 and set screw 32 as shown in FIG. 7. The tape 31 is guided over an idler pulley 34 and is attached to the elevator car,

thus when this tape is wound up onto the drum, the elevator car is lifted to ascend.

The idler pulley '34 has an anti-friction bearing 35 and turns around a pin 36 extending from a lever 37 pivotally supported by a stud 39 secured to frame 1. The lower arm of lever 37 is biased by a spring 40 against a bracket 41 supporting a micro switch 42 which is held closed in the position shown in FIG. 7 when the elevator car is empty. A speed governor 44 has a housing 45 concentric with and forming a part of pulley 34. An end cover 46 secured to housing 45 has a central bearing to accommodate a shaft 47 carrying an eccentric 48 rotatable -relative to an impeller 49, as shown in FIG. 2. The impeller is smaller in diameter than the bore of housing .45 and is held against the internal surface of housing 45,

the point of contact changing with the position of cam 48 relative to impeller 49 as the latter rotates with housing 45, a key 50 secured to housing 45 and engaging slot 51 of impeller 49 serving to provide this rotation. A plurality of slots 52 in impeller 49 accommodate impeller blades 54 shown in FIG. 5. The central notch 55 provides space for a spring 56 biasing the blade into sealing contact with the bore of housing 45. Thus the blades separate the space between the impeller and housing into a number of chambers whose volume varies as the idler pulley revolves. These chambers are filled with a'liquid medium which is pumped from one chamber to another during rotation. The passage to permit the necessary leakage is provided in the form of end clearance of the impeller, for which purpose a circular plate 57 is provided. By selecting a thinner plate, the clearance is increased and the torque of shaft 47 reduced. The pumping liquid may be inserted by removing plug 59. A shaft seal 60 between cap 46 and shaft 47 prevents the escape of the liquid medium. The torque of shaft 47 is transmitted to a bell crank 61 pivoted at 62 to frame 1 and having arms 63 and 64, the latter engaging a link 65 extending from a one-way clutch housing 67, shown in detail in FIGS. 3 and 4. The one-way clutch housing has a bore in which turns a clutch wheel 69 firmly secured to shaft 47 to turn therewith. The housing 67 has a central opening bearing a sprag 70 pivotedat 71 and a spring 72 urging the sprag into engagement with wheel 69. Housing 67, wheel 69, sprag 70, and spring 72 thus form a one-way clutch where shaft 47 may turn clockwise as viewed in FIG. 3 without transmitting appreciable torque to housing 67. Rod is pivotally connected to housing 67 at 74, which location is important to obtain the desirable mechanical advantage when the car is loaded, as will be explained later. Arm 63 of hell crank lever 61 engages an adjusting screw 74 threaded into the end of lever 16 so that the torque transmitted by shaft 47 when the elevator car descends actuates lever 16 in a direction to engage clutch 9, whereby bearings 11 and 14 have to withstand a thrustload. Screw 74 having a left hand thread is provided with a toothed head 75 engaged by a detent spring 76 and a pawl 77 urged by a spring 78 and pivoted to a support 79 extending from arm 64. This arrangement provides an automatic adjustment for the clutch 9 to make up for wear of the friction plates so that manual adjustment is not necessary during the life of the clutch. Each time bell crank 61 is operated pawl 77 is reciprocated tangentially to toothed head 75. If clutch 9 is adjusted, lever 16 has only a short movement, requiring only a short movement of bell crank 61 to engage clutch 9, and the stroke of pawl 77 is less than the spacing between the teeth of head 75 so that the latter is not turned. If the movement is increased due to wear of clutch 9, then pawl 77 catches another tooth and in the return stroke when moving to the position shown in FIG. 1 screw 75 is turned counterclockwise to move lever 16 towards the right for closer engagement. Bell crank 61 also serves to transmit the force of an electric solenoid 80 to lever 16 to engage the clutch 9 when the elevator is to ascend. The solenoid 80 is mounted to frame 1 and has a link 81 to actuate a lever 82 pivoted at 83 to frame 1, lever 82 being positioned relative to arm 64 to actuate the latter when the solenoid is energized and link 81 lifted up. On the other hand, arm 64 may be actuated to engage clutch 9 by the force of governor 44 when the car descends. In order to stop drum 20 and the elevator car when it descends I provide a stop mechanism in the form of a ratchet gear 85 integral with drum 20 engaged by a pawl 86 pivoted at 87 to a link 89 which is free to swing about pivot 90. Thus ratchet gear 85 and pawl 86 when engaged together form means to prevent rotation of drum 20 in one direction. A spring 91 urges the pawl into engagement with ratchet gear 85, while a solenoid 92 secured to the gear box 4 and connected with a link 93 to pawl 86 serves to disengage pawl 86 from gear 85 when the elevator car is to descend. A shock absorber 94 secured to frame 1 serves to absorb or cushion the shock when pawl 86 is engaged and stops wheel 85. Bell crank 61 has an additional arm 96 shown by dotted lines in FIG. 1. This arm connects with a link 97 hooked to a hole 98 in arm 37. The purpose of this arm and link is to partially engage clutch 9 in proportion to the load of the elevator car, however, when the car is empty, spring 40 holds arm 37 in the position shown in FIG. 7 where no force in transmitted by link 97. Hole 98 is sufiiciently large that bell crank 61 may be independently operated by solenoid 80 or governor 44 without hindrance from link 97 when lever 37 is in the position assumed in FIG. 7.

It is apparent that the construction described may be used in a vertical elevator whereby the machine would be in the position shown in FIG. 1, or it could be incorporated in a stair elevator as illustrated in FIG. 9. The driving mechanism is shown in dotted lines as it is housed within a box-like track 100 secured on top of the treads 101 of a stairway. The elevator car 102 has wheels 103 rolling on top of track 100, and another wheel 104 underneath a running board 105 to roll on the side of track 100. A hand rail 107 with knob 108 is secured to the frame of the car. The particular construction of the car and track in shown in detail in my copending application Serial No. 779,718 filed simultaneously with the present application of which it forms no part.

Referring now to the electrical diagram in FIG. 8, there is shown a power circuit energized by line 110 to feed the electric motor 3 through lines 112 and 113 when the solenoid operated switch 114 is closed by solenoid 115. A low voltage control circuit is energized by a transformer 117 from which one line 118 leads directly to solenoid or relay and solenoids 80 and 92, and another lead 120 is connected to a bus bar 121 with an interlock switch or safety switch 122 interposed. This safety switch 122 may represent the overload or slack cable switch commonly used in elevators, but since it forms no part of this invention and is well known in the art, it will not be further described. The bus bars 121, 124, 125, and 126 are located on the track to provide a running connection with the push buttons 127 and 128 and safety switch 129 on car 102. Lead 130 has a sliding shoe in contact with bus bar 121 and leads to switch 129, from there it branches off to one contact of the down button 127 and one contact of the up button 128 as well as to another shoe 131 in contact with bus bar 125. The second contact of the up button 128 is connected to a shoe 134 engaging bus bar 126 and the down button 127 is connected to shoe 135 engaging bus bar 124. The latter is in turn connected by a lead 137 to a call push button switch 138 and to an end switch 139 from where a wire 140 leads to solenoid 92. The second contact of push button switch 138 connects to lead 141 leading to bus bar 125 with interlock switch 42 interposed. This interlock switch is closed when the elevator car is empty, and open when loaded. The same lead before it reaches interlock switch 42 branches off to the call button 142 at the upper landing. Bus bar 126 is connected by a lead 144 to solenoids 80 and 115 with an end switch 145 interposed. This end switch is closed unless the elevator car is at the upper landing. The other end switch 139 is open only when the elevator car is at the bottom landing.

In operation, assuming that the elevator car is at the bottom and at rest, pawl 86 is engaged with ratchet gear 85 and the mechanism is in the position shown. If a person steps on the elevator car, first of all the added tension in tape 30 swings lever 37 to compress springs 40 whereby interlock switch 42 opens so that it is impossible to operate the elevator from call buttons 138 and 142. If the down button 172 is depressed, nothing happens, because end switch 139 is open. Depression of the up" button 128 closes the circuit from transformer 117 via lead 120, bus bar 121, lead 130 with safety switch 129, push button switch 128, shoe 134, bus bar 126, line 144, end switch 145, the coils of solenoids 80 and 115, and lead 118. Energization of solenoid 115 closes switch 114 to energize motor 3, and energization of solenoid 80 actuates lever 82 which in turn operates bell crank 61 urging lever 16 to swing in a clockwise direction to press spider 21 towards clutch plate 29, thereby engaging clutch 9. The thrust required for engagement is not very great because a plurality of friction plates are used so that the torque which clutch 9 is capable of transmitting is greatly increased. The speed of the motor 3 is first reduced by the speed reducer 4 and then it is further reduced by the sprocket gears 5 and 7 and chains 6 to drive drum 20 at the desired speed, clutch 9 and drum 20 turning in unison to wind tape 30 onto drum 20 and causing the elevator car to ascend. If the described control circuit is broken in any way, be it by release of button 128, opening of a safety switch 122 or 129, or opening of end switch 145 when the car reaches the upper landing, solenoids 80 and 115 are deenergized so that switch 114 is opened to deenergize motor 3 and clutch 9 is released, dragging only slightly due to the force exerted by the load of the car through link 97. Accordingly, clutch 9 begins to slip because the momentum of the car anddrum 20 is negligible due to the low speed, and therefore the drum 20 and car come to a quick stop, while the motor continues to turn since its momentum is considerable. To prevent the car from descending after it has stopped, the pawl 86 is provided. This pawl permits the rotation of the drum 20 as the elevator car ascends, but checks it in the opposite direction when the car has come to a stop. This system of stopping makes it necessary to provide a clutch capable of transmitting only a normal torque required to lift the load when the elevator ascends, whereas in conventional elevators the brake torque is several times the normal operating torque even with a greater stopping distance.

Assuming now that the car is again loaded and that the operator depresses down button 127, a control circuit is closed from transformer 117 via the line 120, bus bar 121, lead 130 and safety switch 129, push button switch 127, shoe 135, bus bar 124, end switch 139, lines 140 and 118 to energize solenoid 92. This solenoid pulls pawl 86 free of ratchet gear 85 so that the elevator car is permitted to descend by its own weight, thereby turning drum 20 and unwinding tape 30, while sprocket gear 7 remains stationary so that clutch 9 is slipping. A partial drag of clutch 9 due to the force transmitted by link 96 proportional to the load on the car is not sufiicient to check the descent of the elevator.v The force of link 97 tending to reduce the downward speed of the elevator is augmented by the action of governor 44 which produces only a negligible torque when the speed of idler pulley 34 is low, since this torque is roughly proportional to the square of the speed of rotation. Thus at higher speeds when the elevator car descends rapidly, the torque acting on the shaft 47 increases substantially with any further increase in speed, the result being that an automatic speed control is obtained Where any excessive speed would immediately slow down the speed of rotation of drum 20 by further engaging clutch 9 to act as a brake. Housing 45 of the speed governor and impeller 49 rotate clockwise as viewed in FIG. 2, when the elevator car descends. Comparatively, cam 48 remains stationary. Since this cam is eccentric relative to the axis of housing 45, the chambers filled with fluid between the impeller blades alternately increase and decrease in volume during rotation so that the fluid is continuously forced from one chamber to another by way of the end clearance, as between impeller 49 and spacer plate 57. This restricted flow produces a torque in shaft 47, because cam or eccentric 48 is urged to turn with impeller 49. The torque increases roughly with the square of the speed of rotation of housing 45. In addition, the fluid in the slots 52 also has to be pumped in and out in a similar manner. Depending on the load of the car, the position of lever 37 changes, with no load the position is as shown in FIG. 7 and that of the one-Way clutch in FIG. 3. With a load, spring 40 is compressed, and the one-way clutch assumes the position shown in FIG. 4. Since the pivot point 74 moves closer to a line passing through shaft 47 and parallel with link 65, the mechanical advantage is better when the car is loaded than when it is empty so that a greater force is transmitted to engage clutch 9. When the circuit is broken due to the release of push button 127, the opening of any of the safety switches, or opening of the end switch 139 when the car approaches the bottom landing, solenoid 92 is deenergized so that spring 91 pushes pawl 86 into engagement with ratchet gear 85 to arrest drum 20. The shock is cushioned by bumper 94. The initial arresting force is very light and increases only as bumper 94 is compressed, whereby no objectionable impact is encountered when pawl 86 abuts against one of the teeth of gear 85.

Control of the elevator by depressing the call push buttons 138 or 142 is possible only when the car is empty, because the switch 42 is closed when lever 37 is in the position shown in FIG. 7. Thus if the car is at the lower landing and empty, closing push button switch 142 completes the circuit from transformer 117 via line 120, bus bar 125, interlock switch 42, push button switch 142, end switch 145, and line 118 to energize solenoids and so that the elevator ascends. It stops when this circuit is broken as when end switch 145 is opened, the operation of the mechanism being the same as already described. To call the elevator to the bottom landing when the car is empty by closing push button switch 138 closes a circuit through line 120, bus bar 121, line 130, bus bar 125, switch 42, line 141, push button switch 138, line 137, end switch 139, lines and 118 to energize solenoid 92. The elevator is arrested in the same manner as described before when the circuit is broken, as for instance by end switch 139 when the car reaches the lower station.

Having thus described my invention, I claim:

1. A control system for an elevator having a car to carry loads, comprising driving means consisting of an electric motor and speed reducing means, driven means operatively connected with the car of the elevator to transmit motion to the car, a friction clutch adapted to connect said speed reducing means with said driven means to transmit low speed rotary motion to said driven means, power operated means to engage said clutch and to energize said motor for upward travel of the elevator car, stop means biased to arrest said driven means when said power operated means is not energized to prevent descent of the car, and means responsive to the weight of the car carrying loads to urge said clutch in-to partial frictional engagement in proportion to the weight of the car carrying loads.

2 The construction as claimed in claim 1, controllable means adapted to disengage said stop means to facilitate the descent of said car by slippage of said friction clutch, and means responsive to the speed of said driven means to partly engage said clutch during downward travel of the elevator car to reduce the downward speed of the elevator car. i

3. The construction as claimed in claim 2, and resilient means arranged to oppose the engagement of said clutch, said resilient means being of such force as to prevent the engagement of said clutch during downward travel at low speeds when the elevator car is empty.

4. The construction as claimed in claim 2, and an automatic adjusting mechanism to compensate for wear of said clutch.

5. A control system for an elevator having a car to carry loads, comprising driving means consisting of an electric motor and speed reducing means, driven means including a drum adapted to wind up a towing member having an end attached to the car, a friction clutch adapted to transmit rotary motion from said speed reducing means to said drum to wind up said towing member into said drum and to thereby move said car upwardly, an electric solenoid operatively connected with said clutch to engage said clutch upon energization of said solenoid, means responsive to the tension of said towing member to bias said friction clutch into engagement in proportion to the tension of said towing member to an extent insufficient to prevent the descent of the car, a ratchet gear arranged to turn with said drum, a pawl adapted to engage said ratchet gear to stop said drum, means to bias said pawl into engagement with said ratchet gear, and controllable means to disengage said pawl, whereby stopping of said drum and the elevator car during upward travel is accomplished by deenergizing said motor and said solenoid and whereby engagement of said pawl prevents the descent of the car after the latter has come to a stop.

6. The construction according to claim 5, and cushioning means arranged to absorb the shock of said pawl when stopping said ratchet gear.

7. A control system for an elevator having a car to carry loads, comprising driving means consisting of an electric motor and speed reducing means, driven means including a drum adapted to wind up a towing member ducing means to said drum to wind up said towing member onto said drum and to thereby move said car upwardly, an electric solenoid operatively connected with said clutch upon energization of said solenoid, a ratchet gear arranged to turn with said drum, a pawl adapted to engage said ratchet gear to stop said drum, means to bias said pawl into engagement with said ratchet gear, controllable means to disengage said pawl, whereby stopping of said drum and the elevator car during upward travel is accomplished by deenergizing said motor and said solenoid and whereby engagement of said pawl prevents the descent of the car after the latter has come to a stop, an idler pulley located above said drum to guide and support said towing member leading to the elevator car, a yieldable mechanism to revolubly support said idler pulley, said yieldable mechanism being operatively connected with said clutch to tend to engage said clutch in response to the yield of said yieldable mechanism resulting from the weight of the elevator car, and spring means arranged to oppose the yield of said yieldable mechanism.

8. The construction according to claim 5, a hydraulic rotary type slipping clutch rotatably mounted and operatively connected to an element of said driven means to revolve at a speed in proportion to the speed of said drum, said hydraulic slipping clutch being constructed to produce a force approximately proportional to the square of the speed of rotation of said drum, and means to transmit said force to said friction clutch to tend to engage said friction clutch.

9. The construction according to claim 5, and a spring operatively connected to tend to disengage said clutch.

10. In an elevator having a car to carry loads, in combination, a driving element powered by an electric motor to turn in one direction at a reduced speed, a driven element coaxial with said driving element, a clutch mechanism intermediate said driving element and said driven element to transmit rotary motion from said driving element to said driven element in said one direction to cause the elevator car to ascend, spring means to bias said clutch to be disengaged, towing means permanently associated with said driven element and the elevator car to transmit motion from one to the other, a control mechanism operatively connected with said clutch mechanism to engage said clutch, a stop mechanism associated with said driven element and normally biased to prevent rotation of said driven element in the direction opposite to said one direction in order to prevent descent of the elevator car, means responsive to the tension of said towing means to urge said clutch into engagement with a force in proportion to the tension of said towing means to a degree insufficient to stop the descent of the car, said proportion changing gradually as the weight of the car is increased to increase said force of engagement relative to the tension of said towing means, disengaging means operatively connected with said stop mechanism to disengage said stop mechanism to facilitate the descent of the car when said clutch mechanism is not engaged, and a governor device responsive to the speed of said driven element operatively connected with said control mechanism to engage said clutch mechanism to limit the speed of rotation of said driven element in a direction opposite to said one direction.

11. The construction according to claim 10, where said towing means consists of a flexible metallic tape and said driven means includes a drum where said metallic tape is wound upon itself.

References Cited in the file of this patent UNITED STATES PATENTS 1,338,127 Felt Aug. 27, 1920 1,504,415 Barrett Aug. 12, 1924 1,964,262 Kinzbach June 26, 1934 2,619,195 Scott Nov. 25, 1952 

